This invention generally pertains to a system for providing images of subsurface objects. In particular, the invention provides a system for displaying three-dimensional images of buried pipes and other objects to the operator of an excavator or other such equipment.
A precise map of the subsurface is essential to avoid damaging existing utilities (water, gas, electric lines, etc.) during excavation. For example, prior to digging trenches to install new pipes, a construction crew must know where the existing pipes are buried to avoid damaging them. A lack of accurate maps of construction sites results each year in thousands of damaged utilities and losses of billions of dollars.
Advanced locating technology such as ground penetrating radar and inductive systems can provide accurate three-dimensional (xe2x80x9c3Dxe2x80x9d) maps of buried utilities. However, these maps are not very useful during excavation unless the information they contain is readily accessible to the operator of the excavator. The present invention comprises a system that displays a movie taken with a virtual video camera positioned on the bucket of an excavator. The movie is based on 3D images obtained from advanced locating technology and no physical camera is needed. The virtual camera is created by integrating four position sensors on the excavator with a single ground position sensor. This enables the virtual camera to deliver 3D images of the bucket teeth in relation to the ground and the utilities buried underneath. Existing software can be used without modification to generate the display. For example, MATLAB has the capability of displaying 3D images with user-defined camera position and camera target. MICROSTATION and AUTOCAD also have the ability to produce real-time 3D displays.
Most often the available information about buried utilities is painted onto the street and is thus visible only until the top layer is removed. Obviously this approach makes it difficult for the operator of an excavator to avoid damaging pipes during excavation.
Spectra Precision (www.spectraprecision.com) builds numerous systems that can be adapted to track construction equipment. One such system is called the BUCKET-PRO and displays to the operator of an excavator the 3D location of the bucket in relation to previously imaged utilities. For example, if a trench needs to have a certain fixed depth, the operator can set that depth on his display and continuously monitor the position of the bucket relative to that depth. BUCKET-PRO uses self-tracking laser theodolites and a dual-axis slope sensor.
A sub-surface video system for an excavator is disclosed comprising an excavator with a body, a stick, a main boom, and a bucket, a three-dimensional sub-surface image of an excavation area where the image is positioned with respect to a first fixed coordinate system, a positioning device for determining the position of the bucket with respect to a second fixed coordinate system having a known relation with respect to the first fixed coordinate system, and, a video monitor for displaying the image at a desired depth below the position of the bucket.
In one embodiment of the invention, the positioning device comprises a first positioning device for determining the position of the bucket with respect to the body, and a second positioning device for determining the position of the body with respect to the second fixed coordinate system.
In a further embodiment, the first positioning device comprises a first position sensor to determine the angle between the body and the main boom, and a second position sensor to determine the angle between the main boom and the stick. In another embodiment, the system further comprises a third position sensor to determine the angle between the bucket and the stick.
In yet another embodiment, the second positioning device comprises three reflectors attached to the body, a GEODIMETER device positioned at a fixed point and capable of tracking the three reflectors, thereby determining the position and orientation of the body, a transmitter on the GEODIMETER device for transmitting the position and orientation, and a receiver on the excavator for receiving the position and orientation from the transmitter.
In a further embodiment, the second positioning device comprises a reflector attached to the body, a GEODIMETER device positioned at a fixed point and capable of tracking the reflector, thereby determining the position of the body, a transmitter on the GEODIMETER device for transmitting the position, a receiver on the excavator for receiving the position from the transmitter, and a gyroscope and dual-axis slope sensor on the body for determining the orientation of the body.
In one embodiment, the first coordinate system is a street coordinate system. In a second embodiment, the second coordinate system is a street coordinate system. In a third embodiment, the first coordinate system is a global coordinate system. In a fourth embodiment, the second coordinate system is a global coordinate system.
In an additional embodiment, the image is a volumetric image. In another embodiment, the image is a depth color-coded image.
In one embodiment, the excavator further comprises a ring gear and the positioning device comprises a position sensor in the ring gear to determine the rotational position of the ring gear. In another embodiment, the first fixed coordinate system is the same as the second fixed coordinate system.